Hello, I am having trouble with a PIC16F876A, on an Olimex 28-pin dev board
(see http://www.sparkfun.com/products/18).  The program downloads and
verifies successfully (or so the software tells me) via an meLabs U2 USB
programmer.  In the past, I've had a couple PIC18 chips partially die on me
without losing their ability to be programmed, so I'm wondering if that's
the case here, or if there's something wrong with my code.  I have been
careful about grounding myself while handling both chips, although it's
possible that I forgot at some point while working on it with little sleep.


>
I am trying to toggle all the pins of PORTB as a "hello world" test.  It
works in the simulator, but apparently does nothing on the board.  I have
already checked the supply voltage (+5.05V) and tested both chips on a
breadboard with all the I/O ports connected to GND with 1k resistors as
suggested here http://www.piclist.com/techref/logic/xtrapins.htm.  Still
nothing on my scope, which is an old HP DSO with a 10 MHz sample rate.  Her=
e
is my assembly code:

>
list      p=3D16f876a            ; list directive to define processor

> #include "p16f876a.inc"        ; processor specific variable definitions

>
__CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _RC_OSC & _LVP_OFF &
_DEBUG_OFF & _CPD_OFF

>
; '__CONFIG' directive is used to embed configuration data within .asm file=
..

> ; The lables following the directive are located in the respective .inc
file.

> ; See respective data sheet for additional information on configuration
word.

>
;***** VARIABLE DEFINITIONS

> ;; w_temp        EQU     0x70        ; variable used for context saving

> ;; status_temp   EQU     0x71        ; variable used for context saving

>
;**********************************************************************

> ORG     0x000             ; processor reset vector

> clrf    PCLATH            ; ensure page bits are cleared

> ;   goto    main  ;

>

;; initialize PORTA

> bcf STATUS, RP0 ; select bank 0

> bcf STATUS, RP1

> clrf PORTB

>
bsf STATUS, RP0 ; select bank 1

> movlw 0x06

> movwf ADCON1

> movlw 0x00

> movwf TRISB

>
top:

> bcf STATUS, RP0 ; select bank 0

> movlw 0x00

> movwf PORTB

> movlw 0xFF

> movwf PORTB

> goto top

> END                       ; directive 'end of program'

>
Is there something wrong with this code, or is it definitely a hardware
issue?

>
Thanks,
Jim
--=20
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